1. Field of the Invention
The present invention relates to a power supply system for a vehicle, and in particular, to a power supply system for a vehicle equipped with a power storage device that is chargeable from a source external to the vehicle.
2. Description of the Background Art
In recent years, vehicles equipped with a power supply device and using its electric power to drive a motor, such as electric vehicles, hybrid vehicles, fuel cell vehicles, and the like have been attracting attention as environmentally-friendly vehicles.
In such a vehicle, an externally chargeable configuration has also been under consideration. Generally, in ordinary households, a single-phase 100 V or single-phase 200 V commercial power supply is often used as a power supply for charging.
Japanese Patent Laying-Open No. 2000-354331 discloses a configuration in which, when charging is performed using a 200 V commercial power supply, an exclusive charger is used, and when charging is performed using a 100 V commercial power supply, electric power is received through a neutral point of a field coil of a motor for running a vehicle, and some of diodes used when receiving electric power from the 200 V commercial power supply are commonly used.
To provide environmentally-friendly vehicles, it is important to consider reducing loss during charging as much as possible. In ordinary households, a large amount of electric power cannot be charged from a 100 V system. In contrast, a motor for running a vehicle and an inverter driving the motor can handle a large amount of electric power to be able to respond to sudden acceleration. Instead, a large amount of electric power is consumed to drive the motor and the inverter, and thus loss is increased when a small amount of electric power is handled.
Therefore, since loss is increased when a small amount of electric power of a 100 V system is supplied through a neutral point of a field coil of a motor for running a vehicle as disclosed in Japanese Patent Laying-Open No. 2000-354331, there is still room for improvement in this respect.
Further, in some of ordinary households, a 200 V power supply is also available to operate a large-capacity air conditioner or the like.